use datetime to deal with time in Python

from datetime import datetime, timezone
import time

## UTC --> local time
now = datetime.now()
now_utc = now.replace(tzinfo=timezone.utc)
now_local = now_utc.astimezone()
print(now_local)

## UTC --> UNIX timestamp
time_str = str(now_local).split(".")[0]
time_format = '%Y-%m-%d %H:%M:%S'
now = datetime.strptime(time_str, time_format)
time_tuple = now.timetuple()
utc_now = time.mktime(time_tuple)
print(utc_now)

## switch time zone
import pytz
arrival_nyc = str(now_local).split(".")[0]
nyc_dt_naive = datetime.strptime(arrival_nyc, time_format)
eastern = pytz.timezone('US/Eastern')
nyc_dt = eastern.localize(nyc_dt_naive)
utc_dt = pytz.utc.normalize(nyc_dt.astimezone(pytz.utc))
print(utc_dt)